Effects of preoperative binaural beats on the propofol dose for induction of general anesthesia: a randomized controlled trial

PURPOSE: Brainwave entrainment with low-frequency binaural beats has shown sedative-sparing and anxiolytic effects. We sought to investigate whether the preoperative use of binaural beats could reduce the propofol dose for the induction of general anesthesia. METHODS: We enrolled patients scheduled for elective surgery under general anesthesia in a randomized controlled trial. In the preoperative waiting area, we randomized patients to hear the binaural beats with frequencies of 432 and 431 Hz in the binaural-beats group (N = 34) or silent sound in the control group (N = 35) for 20 min via stereo headphones. For the induction of general anesthesia, we administered 10 mg of propofol every 15 sec until we observed three clinical signs: the loss of response to verbal commands of "open your eyes" (primary outcome), loss of eyelash reflex, and a patient state index of ≤ 50. We collected processed frontal electroencephalography data during the intervention and assessed anxiety scores before and after the intervention. RESULTS: The propofol dose for the loss of response to verbal commands was lower in the binaural-beats group than in the control group (mean [standard deviation], 87 [24] mg vs 105 [32] mg; difference in means, -18 mg; 95% confidence interval, -32 to -5; P = 0.009). There were no significant differences in the delta (P = 0.63), theta (P = 0.28), alpha (P = 0.24), and beta (P = 0.85) bands of the processed frontal electroencephalograms and the anxiety scores (P = 0.50). CONCLUSION: Binaural beats with a frequency of 1 Hz modestly reduced the propofol dose for the induction of general anesthesia, but we observed no significant differences in the processed frontal electroencephalograms and preoperative anxiety levels. STUDY REGISTRATION: ClinicalTrials.gov ( NCT05431881 ); first submitted 9 June 2022.